In recent years, with the multimediatization of information in cellular mobile communication systems as represented by mobile phones for example, transmitting large capacity data such as still images and movies in addition to speech data has become popular. To realize the transmission of high capacity data, a technology in which a high-frequency radio band is used to provide a high transmission rate is studied actively.
However, when a high-frequency radio band is used, although a high transmission rate can be expected in a short distance, attenuation due to transmission distance becomes greater as the distance increases. Accordingly, when the mobile communication system employing a high-frequency radio band is actually operated, the coverage area of each radio communication base station apparatus (hereinafter “base station”) becomes small, which requires that a larger number of base stations be set up. Since the set-up of base stations involves large costs, a technology is strongly demanded for realizing communication services which employ a high-frequency radio band and preventing an increase in the number of base stations.
To meet this demand, various relay transmission technologies are investigated in which radio communication relay station apparatuses (hereinafter “relay stations”) are set up between a radio communication mobile station apparatus (hereinafter “mobile station”) and a base station, and communication between the mobile station and the base station is carried out via these relay stations.
Among conventional channel allocation methods according to relay transmission technologies, there is a method whereby, based on information about nodes where direct transmission is possible and information about other nodes, a channel to be allocated to a link between nodes that are disallowed transmission and nodes that are not disallowed transmission through communication between predetermined nodes is determined so as to differ from the channel between the predetermined nodes (see Patent Document 1).    Patent Document 1: Japanese Patent Application Laid-Open No. 2006-25388